Static pressure regulator



STATIG PRESSURE REGULATOR Bengt Pellmyr and Sven Werner Wallin, Jonkoping, Sweden, assignors to Aktiebolaget Svenska Flaktfabriken, Stockholm, Sweden The present invention relates to a device for maintaining a constant static pressure in a duct or a pipe for a flowing gaseous medium, for instance the distributing pipe in air-conditioning plants.

The device consists of a means of throttling arranged in a section of the duct or similar space, the closing and opening movements of said means for the medium passing said space being maintained by a pressure responsive means sensitive to the pressure difference between two points and subject to the influence of a counter-acting torsional moment on the throttling means.

The invention is mainly characterized in that the throttling means consists of a bow-shaped damper plate which by means of supporting arms is pivotally journalled on an axle in the geometric centre of the bow and arranged perpendicularly with respect to the direction of flow of the medium, and further by a lever mechanism between the pressure responsive means and the throttling means and also by a counter-weight or a spring being fastened to the axle of the throttling means or the lever mechanism for causing a counter-acting moment of torsion on the axle of the throttling means.

By a suitable modification of the invented device the pressure responsive means consists of a membrane to which a mechanical connection acting on the throttling means is fastened, which membrane is surrounded by a casing which is divided by the membrane into two separate spaces each of such spaces being connected to those points of the plant, the pressure difference between which points shall influence the size of the free passage area of the device in such a manner that the size of said area is increased by a reduction of said pressure difference and on the other hand is decreased by a greater pressure diiference.

The mechanical connection between the throttling means and the pressure responsive means may consist of a shaft joined to the membrane and movable by the motion of the membrane in two opposite directions, the other end of the shaft being linked to one end of a bar, the far end of which is pivotally supported at one of the walls of the device, and to which bar furthermore a lever acting on the turning axle of the throttling means is linked by a rod arranged substantially parallel to the shaft,

Other characteristic features of the invention will be set forth in one embodiment described in more detail in the following:

The invention will now be more closely described in connection with the accompanying drawing, in which:

Fig. l is a view in front elevation of a device made in accordance with the present invention;

Fig. 2 is a transverse sectional view taken on the line 2-2 of Fig. l; and

Fig. 3 is a fragmentary sectional view taken on the line 3-3 of Fig. 2.

On the figures of the drawing the walls of the device are designated 3, 5, 7 and 35'. These walls together form a chamber with the openings 1-52 and 18-30 respectively. The chamber is provided with flanges 2, S and rates Patent 9 14, 38 respectively for the fastening of the device, for instance, in apassage of an air-conditioning plant where it is intended continuously to control the static pressure of a flowing gaseous medium. It is intended that the control should be effected by the action of the throttling means, the axle of which is designated 32 and the supporting arms of which are designated 10, 12 joined by means of the detail 11. These arms support a damper plate which in the case illustrated is bow-shaped and is designated 9, 8, 13. Below the chamber is arranged a closed box the parts of which are designated 43, 44. The box forms a casing for a membrane 41 which divides said easing into two different separated spaces. One of these spaces is designated 42 and is, by means of the opening 51 and a corresponding pipe, connected to one of the two points for measuring whilst the other space designated 45, by means of the opening 49 and a corresponding pipe, is connected to the second point for measuring, the intention being that the pressure difference between these two points shall influence the movements of the leading edge of the damper plate upwards to a position shown in full lines at 9 in the drawing, and downwards to the point 53 respectively. The membrane is at its centre reinforced with a disc 46. Between the membrane and the throttling means within the chamber is arranged a mechanical connection. In the embodiment illustrated on the drawing this connection consists of the shaft 24 joined to the membrane disc by means of the nuts 47, 48, the bar 17 and the rod 22', and the lever 26, which lever is fastened to the axle 32 of the throttling means. There can, of course, be other kinds of mechanical connections between the pressure responsive means and the throttling means. 36a, 36b designate a pair of small wheels between which the shaft 24 is guided by its movements upwards and downwards respectively. The designations 23, 21, 16, 22a represent the corresponding linking points in the mechanical connection, and 15 is a support for the bar 17. The designation number 27 stands for a counter-weight which, by means of the screw 28, can be moved along the lever 29, so that in each case of use a greater or lesser torsional moment can be obtained. The lever 29 is clamped around the axle by means of clamping means 31, 34, so that the' action of the gravitation force of the counter-weight on the axle 32 can be regulated by different angles of the lever. Similarly there is a clamping nieans 3t 33 for the lever 26.

Furthermore the controlling device consists of a spring 19 for which by stationary use of said. device can be substituted a weight. The counter-acting force caused by the spring or the weight on the bar 17 determines the relationship between the pressure difference and the free area for the passing gaseous medium. The lower part of the spring is fastened to the lug 20b. The upper part 2AM of the spring can be moved to a number of holes 20 on the bar 1'7, and thus the pressure level can be changed. Likewise the pressure level can be adjusted if a weight is substituted for the spring.

Furthermore in the drawing is shown disc 25 mounted on the axle 32. One of the chamber walls 5 is provided with a window 54 just in front of disc 25. A fixed pointer 55 indicates the position of the throttling means.

The purpose of the device is to maintain continuously and automatically a constant static pressure at point B, for instance situated in a distributing duct connected to the rear end of the device. For this purpose the pressure from two separate points of measuring is conducted to the openings 49 and 51 respectively. If the device is used in an air conditioning plant one of the measuring points can, for instance, be situated within an air distributing duct and the other point can be situated in the place of use (i.e. the place to be air-conditioned), for instance,

just outside a ventilating grille connected to the air distributing duct(s) in the place of use.

The device can also be used for other purposes while still functioning as a pressure governor. The quantity of passing air can thus be calculated by gauging the pressure difference between the points on different sides of the throttling means of the device, for example the points C and D, and by simultaneously noting the size of the opening 53-52 on the scale of the disc 25. By a simple calculation the air quantity can thus be estimated.

We claim:

1. In a device for maintaining the static pressure in a distributing duct for the gaseous medium of an air conditioning plant constant relative to ambient pressure, a housing connected to said duct having a generally rectangular free passage area for the flow of the gaseous medium therethrough, throttling means for said medium comprising a bowed damper plate in the form of a partial cylindrical shell corresponding in axial length to the length of said free passage area and an arcuate distance corresponding to the width of said free passage area, means mounting said plate for rotation about its cylindrical axis comprising an axle mounted in said housing coaxial with said cylindrical axis and parallel to the length direction of said free passage area and radial arms mounted on said axle and supporting said plate thereon, said plate being rotatable between a first limit position out of the free passage area of said housing and a second limit position intersecting said free passage area, means normally maintaining said damper plate in its first limit position comprising a lever on said axle and a counterweight mounted for longitudinal adjustment on said lever, and automatic pressure-responsive means to actuate said damper plate comprising an element operatively connected to said axle and sensitive to the pressure difierence between a point in said distributing duct downstream of said housing and ambient pressure.

2. In a device for maintaining the static pressure in a distributing duct for the gaseous medium of an air conditioning plant constant relative to ambient pressure, a housing connected to said duct having a generally rectangular free passage area for the flow of the gaseous medium therethrough, throttling means for said medium comprising a bowed damper plate in the form of a partial cylindrical shell corresponding in axial length to the length of said free passage area and an arcuate distance corresponding to the width of said free passage area, means mounting said plate for rotation about its cylindrical axis comprising an axle mounted in said housing coaxial with said cylindrical axis and parallel to the length direction of said free passage area and radial arms mounted on said axle and supporting said plate thereon, said 4 plate being rotatable between a first limit position out of the free passage area of said housing and a second limit position intersecting said free passage area, means normally maintaining said damper plate in its first limit position comprising a lever on said axle and a counter-weight mounted for longitudinal adjustment on said lever, and automatic pressure-responsive means to actuate said damper plate comprising a casing in said housing, a membrane substantially parallel to said axle dividing said casing into two separate spaces, one of said spaces being connected to a point in said distributing duct downstream of said housing and the other of said spaces being connected to ambient pressure, whereby said membrane is responsive to the pressure difference between said point and ambient pressure, a shaft projecting perpendicularly from said membrane into said housing and movable by the motion of said membrane longitudinally in opposite directions, a :bar transverse to said shaft and pivoted at one end in said housing and at the other end to said shaft, a rod pivoted at one end to said bar and disposed parallel to said shatt, a crank lever on said damper plate axle for rotating the same, said crank being pivoted to the other end of said rod whereby upon increase in the pressure differential between said point and ambient pressure, said damper plate is displaced toward its second limit position to reduce the flow area through the housing, and upon decrease in the pressure differential between said point and ambient pressure, said damper plate is displaced toward its first limit position, and a spring tensioned between said housing and said bar to bias the damper plate toward its first limit position when the pressure differential between said point and ambient pressure falls below a predetermined minimum value.

References Cited in the file of this patent UNITED STATES PATENTS 190,442 McLoughlin May 8, 1877 427,516 Knickerbacker May 6, 1890 733,757 Spinney July 14, 1903 812,626 Wilson Feb. 13, 1906 991,641 Plantinga May 9, 1911 1,390,521 Fay Sept. 13, 1921 1,490,654 Wylie Apr. 15, 1924 1,656,184 Enz Jan. 17, 1928 1,673,041 Connet June 12, 1928 2,242,667 Cunningham May 20, 1941 2,357,341 Miner Sept. 5, 1944 FOREIGN PATENTS 1,072 Great Britain Apr. 16, 1857 

